Light beams or optical signals are frequently used to transmit digital data. For example, optical signals are used in fiber optic systems for long-distance telephony and internet communication. Additionally, optical signals are frequently used to transmit data between electronic components on a single circuit board or between electronic components on adjacent or nearby circuit boards.
Consequently, optical technology plays a significant role in modern telecommunications and data communication. Examples of optical components used in such systems include optical or light sources such as light emitting diodes and lasers; waveguides; fiber optics; lenses and other optics; photo-detectors and other optical sensors; optically-sensitive semiconductors; optical modulators, and others.
Such systems making use of optical components often rely upon the precise manipulation of optical energy, usually in the form of a light beam, to accomplish a desired task, such as data communication. This is especially true in systems utilizing light for high-speed, low-energy communication between two nodes.
Often, optical resonators are used to selectively filter, switch, or modulate light beams. Ring resonators are a type of optical resonator. Ring resonators typically have an optical waveguide in a closed loop coupled to a tangential waveguide. When light of the appropriate wavelength is coupled to the loop by the tangential waveguide, the ring resonator can serve as a modulator or detector. The amount of energy coupled into the ring resonator depends on a variety of factors including the characteristic resonant optical frequency of the ring.
In some cases, it can be desirable to tune the resonant optical frequency of an optical resonator to counteract instabilities within the system or to allow the resonator to act on a different frequency of optical energy within the tangential waveguide.
Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.